fix #31

I hope with this I fixed the error.

Anwendung/header/header_open_url.c

@@ -10,7 +10,7 @@
  *	zu erleichtern  						 *
  *                                           *
  *-------------------------------------------*
- *      (C) Copyright 2023 Elias Mörz 		 *
+ *      (C) Copyright 2024 Elias Mörz 		 *
  *-------------------------------------------*
  *											 *
  *         Headerpart - open_url			 *
@@ -20,18 +20,25 @@
 
 #include <stdlib.h>
 #include <gtk/gtk.h>
-
+// function that open the browser 
 void open_url(const char *url)
 {
     char url_command[256];
 
-    // use the command 'start' and 'xdg-open' to open the website in the browser    
-#if defined(_WIN32)
-    sprintf(url_command, "start %s", url);
-#elif defined(__linux__)
-    sprintf(url_command, "xdg-open %s", url);
-#endif
+    // check if the program run via wsl
+    if (system("grep -q Microsoft /proc/version") == 0) 
+    {
+        // use the cmd.exe and close it at the end
+        sprintf(url_command, "cmd.exe /C start %s", url);
+    } 
+
+    else 
+    {
+        // use xdg-open on native linux
+        sprintf(url_command, "xdg-open %s", url);
+    }
 
     // run command
     system(url_command);
 }
+